games/vkquake: fix build on 32-bits

./atomics.h:201:9: error: large atomic operation may incur significant performance penalty; the access size (8 bytes) exceeds the max lock-free size (4  bytes) [-Werror,-Watomic-alignment]
        return atomic_fetch_add (atomic, value);
               ^
/usr/include/stdatomic.h:354:2: note: expanded from macro 'atomic_fetch_add'
        atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
        ^
/usr/include/stdatomic.h:247:2: note: expanded from macro 'atomic_fetch_add_explicit'
        __c11_atomic_fetch_add(object, operand, order)

games/vkquake/Makefile

@@ -28,7 +28,7 @@ ALL_TARGET=	# empty
 
 .include	"${.CURDIR}/../quake-data/Makefile.include"
 
-CFLAGS+=	-DDATADIR='\"${Q1DIR}\"'
+CFLAGS+=	-DDATADIR='\"${Q1DIR}\"' -Wno-error=atomic-alignment
 
 OPTIONS_DEFINE=			USERDIRS WAVE FLAC MP3 VORBIS # OPUS
 OPTIONS_RADIO=			MODPLAYER